chi9@quads.uchicago.edu (Lucius Chiaraviglio) (01/31/91)
In article <1991Jan30.144806.14934@aplcen.apl.jhu.edu> jwm@sun4.uucp (James W. Meritt) writes: >BTW: Are the bioagents which are being planned to be used against the >spill taylored to require the presence of sea water? It does NOT look >like a bug I would care to follow the slick back and get underground >away from the ocean. I can just envision the mideast as an area with >food mines... :-( I don't think you need to worry about this, unless oil-eating microbe technology has made a truly awesome leap in the last <4 years. At least as of 1987 (the date of publication of a book on anaerobic microbiology that I have read; I have also found this information elsewhere), no microorganisms are known which can consume hydrocarbons without using free oxygen. Although the amount of oxygen required is not necessarily equal to that needed for complete oxidation of the hydrocarbons, oil deposits are almost certainly completely devoid of free oxygen, at least in their natural state. Even if some oxygen were injected during attempts to get the oil out, it would be rapidly consumed, thus bringing any oil degradation to a halt (assuming that this started in the first place). Besides, even if you pumped oxygen continuously into an oil well (-: not a good idea :-), it would not be much available to oil-eating microbes except at the surface of the oil and in the volume outside of the oil (where they won't be able to eat the oil, of course), because oxygen doesn't dissolve very well in liquid hydrocarbons (which is why you can store sodium and other such water- and air- reactive metals under kerosene; the surface of such metals under kerosene does get oxidized eventually, but it takes many years of storage for the oxidized layer to get really thick). Completely anaerobic decomposition of hydrocarbons is thermodynamically feasible under a variety of reasonable conditions for microbial growth, but no one has found any organisms which do this, much to the discouragement of those who wish to clean up oil spills with microbes, since oil can form oxygen-excluding clots and/or seep into anaerobic areas of soil. I would predict that if such microbes were found or engineered, the threat to underground pools of oil would still be limited, however, by the general lack of water within volumes occupied by oil, and also by the lessening of thermodynamic favorability of decomposition by the buildup of metabolic waste products. With decomposition of the oil limited to its surface and limited in rate by the escape (if any) of metabolic waste products, I would wager that we would still be guzzling the oil faster ourselves than the microbes would. -- | Lucius Chiaraviglio | Internet: chi9@midway.uchicago.edu